Installs a wrapper around HTTP endpoints that generate metrics.

[slackpad]

This generates useful telemetry for assessing the health of clients talking to Consul over HTTP. It rolls up telemetry about endpoints by using this basic structure:

consul.consul.http.<verb>.<parts>

<verb> is the HTTP verb, and <parts> is based on the path that is registered for each endpoint. It won't contain any specific parts of the path like service names or key names. For paths that have a variable part, a _ placeholder will be added.

Here's some example telemetry with this patch active:

[2016-08-09 15:40:00 -0700 PDT][S] 'consul.consul.http.GET.v1.internal.ui.nodes': Count: 1 Sum: 0.562 LastUpdated: 2016-08-09 15:40:08.189480734 -0700 PDT
[2016-08-09 15:40:00 -0700 PDT][S] 'consul.consul.http.GET.v1.coordinate.nodes': Count: 1 Sum: 0.174 LastUpdated: 2016-08-09 15:40:08.191369142 -0700 PDT
[2016-08-09 15:40:00 -0700 PDT][S] 'consul.consul.http.GET.v1.internal.ui.services': Count: 1 Sum: 0.143 LastUpdated: 2016-08-09 15:40:08.210909642 -0700 PDT
[2016-08-09 15:40:00 -0700 PDT][S] 'consul.consul.http.GET.v1.agent.services': Count: 1 Sum: 0.121 LastUpdated: 2016-08-09 15:40:01.398246693 -0700 PDT
[2016-08-09 15:40:00 -0700 PDT][S] 'consul.consul.http.GET.v1.health.service._': Count: 1 Sum: 0.236 LastUpdated: 2016-08-09 15:40:09.441753193 -0700 PDT
[2016-08-09 15:40:10 -0700 PDT][S] '[2016-08-09 15:40:00 -0700 PDT][S] 'consul.consul.http.GET.v1.internal.ui.nodes': Count: 1 Sum: 0.562 LastUpdated: 2016-08-09 15:40:08.189480734 -0700 PDT
[2016-08-09 15:40:00 -0700 PDT][S] 'consul.consul.http.GET.v1.coordinate.nodes': Count: 1 Sum: 0.174 LastUpdated: 2016-08-09 15:40:08.191369142 -0700 PDT
[2016-08-09 15:40:00 -0700 PDT][S] 'consul.consul.http.GET.v1.internal.ui.services': Count: 1 Sum: 0.143 LastUpdated: 2016-08-09 15:40:08.210909642 -0700 PDT
[2016-08-09 15:40:00 -0700 PDT][S] 'consul.consul.http.GET.v1.agent.services': Count: 1 Sum: 0.121 LastUpdated: 2016-08-09 15:40:01.398246693 -0700 PDT
[2016-08-09 15:40:00 -0700 PDT][S] 'consul.consul.http.GET.v1.health.service._': Count: 1 Sum: 0.236 LastUpdated: 2016-08-09 15:40:09.441753193 -0700 PDT
[2016-08-09 15:40:10 -0700 PDT][S] 'consul.consul.http.GET.v1.kv._': Count: 3 Min: 0.114 Mean: 0.150 Max: 0.179 Stddev: 0.033 Sum: 0.450 LastUpdated: 2016-08-09 15:40:19.244495412 -0700 PDT': Count: 3 Min: 0.114 Mean: 0.150 Max: 0.179 Stddev: 0.033 Sum: 0.450 LastUpdated: 2016-08-09 15:40:19.244495412 -0700 PDT

You can see the KV example, where we have consul.consul.http.GET.v1.kv._. This prevents leaking sensitive information and also prevents an explosion of telemetry.